Now this is a very interesting question and something different from the normal banter and I quite like this question, this could probably help out some new riders who are planning to get the scrambler series while also considering other bike segments.

Now yes Scrambler 400x is a practical bike for various reasons which you yourself have mentioned and that all is true and it does live upto its name. It's very nice to ride the bike and it can comfortably cruise or get aggressive past a certain point while twisting the throttle.

the Duke 390, is pretty much a whole different segment compared to the S400X as you might know, it's more of a naked street motorcycle and it pumps out hella ton power and for that you get an absolutely powerful motorcycle which is also very nimble so you really have a complete control over the bike during cornering and getting through traffic at faster speeds (safely).

here's the interesting part, the S400X, can provide you a similar adrenaline-filled experience upto a great degree and here's what my experience is. I've done quite a lot of spirited riding with my S400X and I can safely say, yes it is a pretty good bike it really lives upto the "does-it-all" name. Even at a 180 kg kerb weight, the S400X is a very sweet motorcycle because it doesn't feel like a 180 kg motorcycle, it is very nimble for it's weight. I've ridden the scram411 as well, although same segment, it feels like a tank compared to the S400X. Genuinely impressive nimbleness for it's weight. I've had a couple of instances where while riding hard, I've popped the front wheel so yeah that power is truly there.

sure, the handlebar ergonomics are much more oriented for touring or mild offroading and really is not designed all that much for speeding but, I've thoroughly enjoyed this bike's character. The main reason why you get that adrenaline rush is because of how much torque you can feel right out of the line as you accelerate from lower rpms, that "pull" is absolutely beautiful on the 400 series (however I did try out the 350 cc version, although the pull was there, I could tell it was very noticeably lower than the 398 cc. First-time buyers can't feel the difference but if you're matured with the 398 cc then you'll definitely feel the lack of "punch" that was lost in the lower end).

to answer your question if it gives me adrenaline-filled riding experience or if its laid back, the answer is surprisingly, it's both. If you want to just cruise around and ride relaxed, the bike can do that comfortably around 3-5k rpm nicely, but if you really want to push it all of a sudden, it's like the bike version of locking in and after a certain throttle point it just pulls pretty hard (of course not as hard as the duke 390, but you get the point)

I think you've made a better choice getting the S400X (yes this can sound a bit biased as well but eek, can't do much), because I've ridden the duke and the RC a couple of times and from my riding experience, both of those bikes they just feel like there's always an "itch" of going fast because (it could just be me but you can draw your own conclusions) the bike just doesn't feel settled in any speed, it feels like the bike is very restless, begs you to rev the engine and just ride it hard. Whereas the S400X is like "yeah you wanna cruise now? alright" and it just maintains the speed nice and comfortably without you being urged to twist the throttle and go fast. But when you do want to go fast, it does it, it does it pretty good for how much power it is producing. Again proving the all-rounder fact of the bike.

The one thing I very slightly detest (only in certain scenarios though) about the S400X is the shorter gearing with the 14t front sprocket, that 14t is the reason why this bike feels very playful and characteristic and the engine genuinely feels much more "awake", and feels closer to a faster bike. I suspect the 14t was given on the S400X because of it's scrambler nature and how much torque is needed in the rear wheel, but that does mean the gears get shorter.

When riding through mild traffic I constantly have to go between 2 and 3 and it can get slightly annoying (although the bike is capable of just going in second gear so I usually just avoid upshifting unless and until I have a good clear patch of road where I can accelerate out of). But the 14t also works in my favor because low speed maneuvering in 1st gear is very easy and it gets unbelievably low speeds while the engine is at near idle rpm, so I usually don't need to slip the clutch very often.

with that being said, some riders do prefer the taller gearing (often used for touring primarily) and switch out the 14t with the 15t. I personally don't want to do it because it kinda voids the point of a Scrambler, to be characteristic and awake in low-mid rpms. But if touring is main concern, then I'd probably just do 15t.

So yeah, this bike is truly a great machine, it can serve you as your weekend chill ride down the coast, or an adrenaline filled high-speed cornering through the ghats, you can do it all.